Conductivity of a 2DEG in Si/SiGe heterostructure near metal- insulator transition: role of the short and long range scattering potential

Abstract

We report the observation of a metal-insulator transition (MIT) in a two- dimensional electron gas (2DEG) in a Si/SiGe heterostructure at zero magnetic field. On going through the MIT we observe the corresponding evolution of the magnetic field induced transition between the insulating phase and the quantum Hall (QH) liquid state in the QH regime. Similar to the previous reports for a GaAs sample, we find that the critical magnetic field needed to produce the transition becomes zero at the critical electron density corresponding to the zero field MIT. The temperature dependence of the conductivity in a metallic-like state at zero field is compared with the theory of the interaction corrections at intermediate and ballistic regimes $k_{B}T\tau /\hslash \ge 1$. The theory yields a good fit for the linear part of the curve. However the slope of that part of ${\sigma }_{xx}(T)$ is about two times smaller than that reported in other 2D systems with similar values of $r_s$. At the same time, the recent theory of magnetoresistance due to electron-electron interaction in the case of arbitrary $k_{B}T\tau /\hslash$, smooth disorder and classically strong fields does not seem to be quite adequate for the description of the parabolic magnetoresistance observed in our samples. We attribute these results to the fact that neither of these theories deals with the whole scattering potential in a sample but leaves either its long range or its short range component out of consideration.

arXiv comment8 pages, 5 figures

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• Investigation of Mobility Limiting Mechanisms in Undoped Si/SiGe Heterostructures
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• Quantum corrections to the conductivity and Hall coefficient of a two-dimensional electron gas in a dirty AlGaAs/GaAs/AlGaAs quantum well: from the diffusive to the ballistic regime
• Quantum corrections to the conductivity and Hall coefficient of a 2D electron gas in a dirty AlGaAs/GaAs/AlGaAs quantum well: transition from diffusive to ballistic regime
• Conductance quantization in etched Si/SiGe quantum point contacts
• Crossover from weak localization to Shubnikov-de Haas oscillations in a high mobility 2D electron gas
• Magnetotransport of electrons in quantum Hall systems
• Modulation of the high mobility two-dimensional electrons in Si/SiGe using atomic-layer-deposited gate dielectric
• Measurements of the magnetic properties of conduction electrons
• Termination of two-dimensional metallic conduction near metal-insulator transition in a Si/SiGe quantum well
• Charge Transport in a Spin-Polarized 2D Electron System in Silicon